hydrate

American  

[hahy-dreyt] / ˈhaɪ dreɪt /

noun

1. any of a class of compounds containing chemically combined water. In the case of some hydrates, as washing soda, Na 2 CO 3 ⋅10H 2 O, the water is loosely held and is easily lost on heating; in others, as sulfuric acid, SO 3 ⋅H 2 O, or H 2 SO 4 , it is strongly held as water of constitution.

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verb (used with or without object)

hydrated, hydrating

1. to combine chemically with water.

hydrate British  

/ ˈhaɪdreɪt /

noun

1. a chemical compound containing water that is chemically combined with a substance and can usually be expelled without changing the constitution of the substance

2. a chemical compound that can dissociate reversibly into water and another compound. For example sulphuric acid (H 2 SO 4 ) dissociates into sulphur trioxide (SO 3 ) and water (H 2 O)

3. (not in technical usage) a chemical compound, such as a carbohydrate, that contains hydrogen and oxygen atoms in the ratio two to one

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verb

1. to undergo or cause to undergo treatment or impregnation with water

hydrate Scientific  

/ hī′drāt′ /

1. A compound produced by combining a substance chemically with water. Many minerals and crystalline substances are hydrates.

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1. To combine a compound with water, especially to form a hydrate.

2. To supply water to a person in order to restore or maintain a balance of fluids.

Other Word Forms

• hydration
  noun
• hydrator
  noun

Etymology

Origin of hydrate

First recorded in 1795–1805; hydr- ¹ + -ate ²

Explanation

To hydrate is to add or absorb water. It's hot outside — don't forget to hydrate by drinking plenty of water! If you want to sound fancy, you can use the word hydrate every time you get a drink of water. Along with most organisms, we need to hydrate, or ingest water, to stay alive. This verb is also commonly used to mean "moisturize," as in "this magic cream will hydrate your skin like you won't believe!" As a noun, hydrate refers to a chemical compound that includes water molecules. A French chemist coined the noun in 1800 from the Greek hydor, "water."

Example Sentences

"You could run into the extremes of eating too much, where if you're not drinking enough water to hydrate and exceed the amount of soluble and insoluble fiber, you can get constipated," Lee said.

From Science Daily • Mar. 8, 2026

By the time of her death she was refusing to drink, despite desperate efforts to hydrate her, and the inquest was told this was sign of hydrophobia, a fear of water commons in rabies cases.

From BBC • Mar. 5, 2026

Most sports demand constant motion, but skating involves working on a trick for maybe an hour, then desperately seeking cover from the sun to hydrate.

From The Wall Street Journal • Aug. 21, 2025

“This allows it to fully hydrate and magically transform into a cohesive piece of dough that’s ready to be rolled out.”

From Salon • Jan. 30, 2025

I gag thinking about where they’ll get the liquid to hydrate the meals.

From "The Last Cuentista" by Donna Barba Higuera